Exploring Mirum Pharmaceuticals, Inc. (MIRM) Investor Profile: Who’s Buying and Why?

You're looking at Mirum Pharmaceuticals, Inc. (MIRM) and trying to figure out if the smart money is still buying, and honestly, the ownership structure is telling a fascinating story you need to unpack before making a move. The headline is that institutions own a staggering 114.06% of the company's float as of October 2025, a figure that signals both extreme conviction from big players and a high level of short interest, which is a defintely volatile mix. With the stock price hitting around $70.97 per share in early November 2025, and the company guiding for full-year 2025 revenue of $500 million to $510 million, the fundamental growth story is strong, but the technical picture is a tug-of-war.

So, why are giants like Frazier Life Sciences Management, L.P. and Janus Henderson Group Plc holding massive positions, while a major firm like JPMorgan Chase & Co. slashed its shares by over 79% recently? Are the buyers betting on the continued success of their commercial medicines, or are the sellers worried about the clinical pipeline risks, like the Volixibat study data expected in 2026? We're going to dive into the 13F filings, look past the $3.56 billion market capitalization, and show you exactly who is accumulating and who is quietly exiting this rare-disease biotech.

Who Invests in Mirum Pharmaceuticals, Inc. (MIRM) and Why?

You're looking at Mirum Pharmaceuticals, Inc. (MIRM) and trying to figure out who is driving the stock's impressive run-up over 74% between November 2024 and November 2025-and what their playbook is. The direct takeaway is that Mirum is overwhelmingly an institutional growth story, with major players betting on the company's transition to profitability and its specialized pipeline in rare liver diseases. It's a high-conviction play on commercial execution and future catalysts.

Key Investor Types: The Institutional Dominance

The investor base for Mirum Pharmaceuticals, Inc. is heavily skewed toward professional money managers. As of the most recent filings, the company has 468 institutional owners, who collectively hold a massive number of shares. This isn't a stock driven by retail chatter; it's a staple in specialized biotech and growth-focused portfolios.

The ownership breakdown shows just how concentrated the professional interest is. Here's the quick math on who owns the float:

• Institutions (Mutual Funds, Pension Funds): Approximately 82.4% of shares.
• Venture Capital (VC) and Private Equity (PE) Firms: Around 11.6%.
• Hedge Funds: Roughly 4.73%.
• Individual Insiders (Executives, Directors): Only 1.21%.

This means nearly all the stock is held by entities with deep research teams. When you see names like BlackRock, Inc. and Vanguard Group Inc. on the list of top holders, you know the stock is vetted for long-term inclusion in broad-market funds, while specialist firms like Frazier Life Sciences Management, L.P. and Citadel Advisors Llc signal conviction in the biotech thesis.

Investment Motivations: Growth and Profit Turnaround

Mirum doesn't pay a dividend, which is defintely typical for a biotech company focused on reinvesting for growth. So, what's the draw? It boils down to a clear growth path and a recent, critical shift in financial health.

The main attraction is the commercial success of their flagship product, LIVMARLI (maralixibat), which treats cholestatic pruritus in Alagille syndrome. In the second quarter of 2025, LIVMARLI net product sales hit $88.2 million, an 87% year-over-year increase. This strong performance led management to raise its full-year 2025 revenue guidance to the upper end of the $500 million to $510 million range.

The second major motivator is the profit turnaround. In the third quarter of 2025, Mirum reported a net profit, posting earnings per share (EPS) of $0.05, which is a significant milestone for a growing biotech. This move from a net loss to net income gives investors confidence that the company can achieve operating leverage (scaling revenue faster than costs). Plus, the pipeline provides a durable growth engine:

• LIVMARLI Expansion: Seeking label expansion for other rare cholestatic conditions.
• Volixibat: Late-stage trials (VISTAS and VANTAGE studies) for primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC), with key data readouts expected in 2026.
• Cash Position: A healthy balance sheet with $321.7 million in unrestricted cash and investments as of June 30, 2025, which funds pipeline development without immediate need for dilutive equity raises.

If you want to dive deeper into the core numbers, you should check out Breaking Down Mirum Pharmaceuticals, Inc. (MIRM) Financial Health: Key Insights for Investors.

Investment Strategies: Growth, Value, and Catalysts

The strategies employed by these institutional holders can be categorized into three main buckets, all of which are common in the biotech sector:

The core strategy remains growth investing. Analysts have an average target price of $87.11, suggesting a potential upside of over 20% from the stock's November 2025 price of around $70.97. What this estimate hides, though, is the inherent risk of clinical trials; a setback in the Volixibat program, for instance, could quickly challenge that bullish fair value. Still, the consensus is strong, with 11 buy ratings and zero hold or sell recommendations, showing a high level of confidence in the company's trajectory.

Institutional Ownership and Major Shareholders of Mirum Pharmaceuticals, Inc. (MIRM)

If you're looking at Mirum Pharmaceuticals, Inc. (MIRM), the first thing to understand is that institutional money overwhelmingly drives the stock. As of the third quarter of fiscal year 2025, institutional investors-the mutual funds, pension funds, and asset managers-held a massive number of shares, which is typical for a growth-focused biotech company with approved products like LIVMARLI®. This deep institutional backing is defintely a vote of confidence in their rare disease pipeline.

The total value of institutional holdings in Mirum Pharmaceuticals, Inc. reached approximately $4.163 billion as of the September 30, 2025, filings. This represents a significant portion of the company's market capitalization, reflecting a strong belief in the commercial success of their therapies for cholestatic liver diseases. This is a high-conviction stock for a lot of big players.

Top Institutional Investors and Their Stakes

The institutional investor profile for Mirum Pharmaceuticals, Inc. is dominated by specialized healthcare funds and major asset managers. These are not small, passive bets; these are strategic positions taken by firms that have done deep diligence on the company's drug development and commercialization strategy. The top holders, based on the most recent Q3 2025 13F filings, show a clear commitment:

• Frazier Life Sciences Management, L.P. leads the pack with a substantial stake.
• Janus Henderson Group Plc holds a significant position, often indicative of a long-term growth view.
• BlackRock, Inc., one of the world's largest asset managers, maintains a core holding.
• Vanguard Group Inc. and Eventide Asset Management, Llc round out the top five, representing both passive index funds and active sector-focused strategies.

Here's the quick math on the top four institutional holders, illustrating the size of their commitment as of September 30, 2025:

Recent Shifts in Ownership: Buying vs. Selling

Looking at the Q3 2025 filings, the overall trend for Mirum Pharmaceuticals, Inc. has been one of net accumulation. Institutional investors increased their total holdings percentage from 94.02% to 95.62% between December 2024 and March 2025, and the number of institutional owners saw a recent quarter-over-quarter change of 6.12%. This suggests a rising level of institutional interest as the company continues to execute on its commercial strategy for its approved medications like LIVMARLI® and CHOLBAM®.

However, the picture is not uniform. For example, while BlackRock, Inc. increased its stake by adding 25,343 shares in the third quarter of 2025, other major holders showed some trimming. Janus Henderson Group Plc decreased its position by -4.558% (or 238,691 shares), and Bvf Inc/Il significantly cut its stake by over a million shares. This divergence is healthy; it shows active portfolio management, where some funds take profits while others see a new entry point or a better long-term value proposition. This is a stock where conviction is high, but managers are still actively managing risk.

The Impact of Institutional Investors on Strategy and Stock Price

In a biotech firm like Mirum Pharmaceuticals, Inc., institutional investors play a crucial role beyond just providing liquidity. Their large positions act as a stabilizing force for the stock price, but they also exert significant influence on corporate strategy. These major shareholders, especially those filing a Schedule 13D (indicating intent to actively pursue a change in business strategy), often have direct lines to management and the board.

Their continued buying, especially following the Q3 2025 revenue report of $133.01 million-a 47.1% year-over-year increase-signals confidence in the commercial ramp-up of their rare disease portfolio. For you, the individual investor, this institutional backing is a critical risk-mitigation factor. It suggests that the market's most sophisticated players believe the company can overcome the anticipated full-year 2025 EPS loss of -$1.43 and achieve profitability. Their focus is on the long-term potential of the drug pipeline, which is the real story here. To understand the foundation of this confidence, you can look into the company's background and core business model: Mirum Pharmaceuticals, Inc. (MIRM): History, Ownership, Mission, How It Works & Makes Money.

Key Investors and Their Impact on Mirum Pharmaceuticals, Inc. (MIRM)

The investor profile for Mirum Pharmaceuticals, Inc. (MIRM) is dominated by institutional money, which signals strong conviction in the company's commercial-stage rare disease portfolio. As of March 2025, institutional investors held approximately 95.62% of the shares, a significant concentration that often leads to less volatility from retail trading noise. This is defintely a stock where the big funds call the shots.

You need to know who these major players are, because their movements-buying, selling, or even just holding-can dictate the short-term price action. The presence of specialized biotech funds among the top holders suggests a deep dive into the clinical and commercial potential of their key product, Livmarli (maralixibat), which is approved for Alagille syndrome and PFIC (Progressive Familial Intrahepatic Cholestasis).

The Heavy Hitters: Who Owns the Largest Stakes?

The largest shareholders are primarily institutional, managing billions in assets. Their positions reflect a belief that Mirum Pharmaceuticals, Inc. can continue to grow its market share in the niche ultra-orphan drug space. Their collective influence means company strategy, especially around drug development and commercialization, is constantly under their scrutiny.

Here is a snapshot of the top institutional holders, based on filings closest to the end of the third quarter of 2025:

Frazier Life Sciences Management, L.P., a venture capital firm focused on life sciences, holds the largest stake, which is a classic signal in biotech: a specialist investor is heavily invested in the long-term success of the pipeline. BlackRock, Inc. and The Vanguard Group, Inc. are also in the top tier, which is typical for large-cap funds tracking major indices, but their sheer size still gives them considerable sway. You can see how the company achieved its recent financial success in Breaking Down Mirum Pharmaceuticals, Inc. (MIRM) Financial Health: Key Insights for Investors.

Recent Moves and the Generic Risk

The second and third quarters of 2025 saw significant institutional activity, mostly on the buy side, reflecting optimism following strong commercial performance. For instance, Frazier Life Sciences Management L.P. increased its stake by 3.4% in the first quarter of 2025, a clear vote of confidence. Plus, new money flowed in from firms like Los Angeles Capital Management LLC, which purchased a new stake valued at approximately $435,000.

However, not all moves were increases. Janus Henderson Group Plc, another top holder, trimmed its position by about 4.56% as of September 30, 2025. This tells you some funds are taking profits or rebalancing, but the net institutional trend remains positive.

The biggest risk on the horizon-and one that will test investor conviction-is the generic challenge to Livmarli. Mirum Pharmaceuticals, Inc. received a Paragraph IV Certification Notice Letter from Sandoz, Inc. in November 2025, seeking approval for a generic version. This immediately triggers a period of uncertainty. The company plans to file a patent infringement suit, which, if done within 45 days, will block final FDA approval for Sandoz's generic for up to 30 months, or until a court decision.

• Strong Q3 2025 revenue of $133.0 million drove institutional buying.
• The Sandoz generic challenge creates a near-term legal risk.
• Insider activity shows net buying over the last three months, a positive sign.

Here's the quick math: the 30-month stay buys the company time to expand its market and pipeline, but the legal battle is a significant operating expense and overhang. The market is pricing in the current commercial success-Q3 2025 brought the company its first positive net income of approximately $3 million-but the long-term value hinges on defending that Livmarli revenue stream.

Market Impact and Investor Sentiment

You're looking at Mirum Pharmaceuticals, Inc. (MIRM) and seeing a biotech company with a lot of institutional backing, and you're right to focus on who's buying. The current investor sentiment for Mirum is defintely bullish, driven by strong commercial execution, but it's a nuanced picture you need to understand.

Institutional investors-the big money-have a clear positive sentiment, increasing their collective holdings to an impressive 95.62% of the company's shares as of March 2025. This shows a high conviction level in the long-term story, especially the commercial success of their flagship product, Livmarli (maralixibat). But here's the kicker: company insiders, like executives and directors, have been net sellers in the most recent quarter, which is a signal that always warrants closer examination.

The core of this positive sentiment rests on Mirum's focus on rare liver diseases. You can see their strategic clarity in their Mission Statement, Vision, & Core Values of Mirum Pharmaceuticals, Inc. (MIRM).

Who's Driving the Institutional Buying?

The largest institutional holders are major biotech and growth-focused funds, signaling that they view Mirum as a high-growth pharmaceutical play. These firms aren't just holding; they are actively managing their positions, which is why we track their 13F filings so closely.

Here's a snapshot of the largest institutional stakes as of the end of Q3 2025, which gives you a clear view of the conviction levels:

The sheer size of the stake held by Frazier Life Sciences Management LP, over 6.79 million shares, tells you a major biotech specialist sees significant upside. This is a vote of confidence that outweighs a lot of the noise.

Market Response: The Earnings Catalyst

The market has responded decisively to Mirum's operational performance in 2025. When a biotech company starts delivering consistent commercial beats, the stock moves fast. You saw this clearly with the Q2 2025 earnings report.

• Q2 2025 revenue hit $128 million, comfortably beating the analyst consensus.
• The stock surged by 10.83% on August 7, 2025, right after the positive FDA feedback and earnings release.
• Shares trended up another 9.8% on August 11, 2025, as analysts digested the improved outlook.

This positive momentum is why the stock price has appreciated significantly, with the share price on November 4, 2025, at $70.97, representing a 74.29% increase from the price a year prior. Strong revenue growth, like the 47.1% year-over-year increase reported in the Q3 2025 revenue of $133.01 million, is what fuels this kind of market reaction.

Analyst Consensus: Mapping Near-Term Opportunity and Risk

Wall Street analysts are largely in the 'Strong Buy' camp, but their perspectives also map out the near-term risks. The consensus price target is in the $81.58 to $86.09 range, suggesting a solid double-digit upside from the current trading price of around $71.44 (as of November 14, 2025).

The key opportunity they see is the continued commercial ramp of Livmarli and the pipeline. Cantor Fitzgerald, for instance, raised their price target to $95.00 on November 5, 2025, after the company's strong Q3 performance, which included a surprising positive EPS of $0.05 against an expected loss of ($0.10). Here's the quick math on the full year: the consensus FY 2025 revenue forecast is now around $515.92 million, with an expected loss per share (EPS) of around ($0.70), a significant improvement from earlier estimates.

What this estimate hides, however, is the patent risk. On November 17, 2025, Mirum Pharmaceuticals, Inc. received a Paragraph IV Certification Notice from Sandoz, indicating an intent to launch a generic version of Livmarli. This is a major, near-term risk. Mirum plans to file a patent infringement suit, which could delay the generic's FDA approval for up to 30 months, but you need to factor in the potential for a prolonged legal battle and the eventual loss of exclusivity.